www.semtech.com
Page 49
ADVANCED COMMUNICATIONS & SENSING
USER GUIDE
SX8724SEVK
Evaluation Kit for SX8724S Data Acquisition System
ACS - Revision 1.0 May 2011
© Semtech Corp.
17.10 ZoomingADC™ Benefits
Now that we zoomed on the signal, we can compare the zoom performances with and without the offset
compensation. To make a comparison do as follow:
Without Zoom (gain only)
1. On the graph, set the full scale view: right click on the panel and select
Undo All Zoom/Pan
option to reset
the display range to the default full scale range.
2. Set the configuration to Gain = 225 & no offset cancellation as in
17.5.2. Rough Gain Configuration
section.
3. Then blow in the sensor tube (try to make the maximum signal span).
The signal span correspond to 31923–28599 = 3324 bits. The result should look like the picture below:
With Zoom (gain and offset)
Now set the parameters as defined in
17.6.4. Final Gains Configuration
(Gain 825, offset -1.58 x V
REF
). The
result should look like the picture below:
The signal span is 11743–1374=10370 bits which corresponds to a
320% gain on the signal reading
allowing you to have more consistent readings.
Figure 41. Signal Span Using Rough Gain Setting
Figure 42. Signal Span Using Zooming Settings
3324 bits span
10’370 bits span
